X0609 4 2026-07-28 0001559053 PROTHENA CORP PUBLIC LTD CO PRTA 0001457013 Nguyen Tran false C/O PROTHENA BIOSCIENCES INC 1800 SIERRA POINT PARKWAY BRISBANE CA 94005 false true false false Chief Strategy Officer and CFO false Ordinary Shares, par value $0.01 per share 2026-07-28 4 M false 57000 A 97205 D Ordinary Shares, par value $0.01 per share 2026-07-28 4 D false 57000 8.56 D 40205 D Restricted Stock Units 2026-07-28 4 M false 57000 0 D Ordinary Shares 57000 0 D Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting. These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 95,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4. These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 95,000 RSUs reported in Table I (38,000 RSUs) are subject to vesting. /s/ Michael J. Isaacs, as Attorney-in-Fact for Tran B. Nguyen 2026-07-30